The invention relates to new and useful improvements in an automation system for the control and regulation of machines and systems used e.g. in the plastics industry, in particular blow molding machines. More particularly, the invention relates to such automation systems having programmable logic controllers (PLC), which can be used to implement the open-loop and closed-loop control functions of the machines and systems as desired, and which have at least one operating and monitoring unit and a local bus (user platform). The programmable logic controllers (PLC) are provided with digital technology blocks which simulate electrical, application-specific switching details. These technology blocks are used to implement, in a modular fashion, the open-loop and closed-loop control functions that are necessary for a particular application. They can be connected to one another and to the user platform via data interfaces.
Plastics processing machines controlled by means of programmable logic controllers are known in the art. One representative such system is described in U.S. Pat. No. 5,062,052, the disclosure of which is incorporated herein by reference. In the past, it has been customary to use special hardware components, i.e. special assemblies, to automate machines in the plastics industry, in particular those for blow molding and injection molding. These known special assemblies have hardware and software which are specially designed for a specific, respective task. The results achieved with the plastics machines are good, but the control systems are highly complex. To cope with new or modified products, both the control programs and the special assemblies have to be adapted to the new machine conditions. Modifications sometimes also require new hardware components.